A compressor which compresses gases and supplies the compressed gases to machines or the like connected to a downstream side of a gas system is known. As this compressor, there is a compressor in which a gas flow rate for a compressor body is adjusted by arranging an inlet guide vane (IGV) at an upstream side and adjusting the degree of opening of the IGV.
In Patent Document 1, technology of appropriately controlling a degree of opening of the IGV and performing an optimum operation even when a performance difference occurs between two first-stage compressor bodies among a plurality of compressor bodies is disclosed as related technology.